Co-fabrication of vertical diodes and fin field effect transistors on the same substrate

ABSTRACT

A method of forming a vertical finFET and vertical diode device on the same substrate, including forming a channel layer stack on a heavily doped layer; forming fin trenches in the channel layer stack; oxidizing at least a portion of the channel layer stack inside the fin trenches to form a dummy layer liner; forming a vertical fin in the fin trenches with the dummy layer liner; forming diode trenches in the channel layer stack; oxidizing at least a portion of the channel layer stack inside the diode trenches to form a dummy layer liner; forming a first semiconductor segment in a lower portion of the diode trenches with the dummy layer liner; and forming a second semiconductor segment in an upper portion of the diode trenches with the first semiconductor segment, where the second semiconductor segment is formed on the first semiconductor segment to form a p-n junction.

BACKGROUND Technical Field

The present invention relates to co-fabricating a vertical field effecttransistor (VFET) structure with a vertical diode, and more particularlyto the co-integration of a VFET and companion p-n vertical diode on thesame substrate.

Description of the Related Art

A Field Effect Transistor (FET) typically has a source, a channel, and adrain, where current flows from the source to the drain, and a gate thatcontrols the flow of current through the channel. Field EffectTransistors (FETs) can have a variety of different structures, forexample, FETs have been fabricated with the source, channel, and drainformed in the substrate material itself, where the current flowshorizontally (i.e., in the plane of the substrate), and finFETs havebeen formed with the channel extending outward from the substrate, butwhere the current also flows horizontally from a source to a drain. Thechannel for the finFET can be an upright slab of thin rectangular Si,commonly referred to as the fin with a gate on the fin, as compared to aMOSFET with a single gate in the plane of the substrate. Depending onthe doping of the source and drain, an n-FET or a p-FET may be formed.

Examples of FETs can include a metal-oxide-semiconductor field effecttransistor (MOSFET) and an insulated-gate field-effect transistor(IGFET). Two FETs also may be coupled to form a complementary metaloxide semiconductor (CMOS), where a p-channel MOSFET and n-channelMOSFET are coupled together.

As MOSFETs are scaled to smaller dimensions, designs and techniques areemployed to improve device performance. Vertical transistors areattractive candidates for scaling to smaller dimensions. In verticaltransistors, the source/drain regions are arranged on opposing ends of avertical channel region. Vertical transistors may provide higher densityscaling and allow for relaxed gate lengths to better control deviceelectrostatics without sacrificing the gate contact pitch size.

SUMMARY

A method of forming a vertical fin field effect transistor (finFET) anda vertical diode device on the same substrate includes forming a channellayer stack on a heavily doped layer; forming one or more fin trenchesin the channel layer stack; oxidizing at least a portion of the channellayer stack inside the one or more fin trenches to form a dummy layerliner; forming a vertical fin in at least one of the one or more fintrenches with the dummy layer liner; forming one or more diode trenchesin the channel layer stack; oxidizing at least a portion of the channellayer stack inside the one or more diode trenches to form a dummy layerliner; forming a first semiconductor segment in a lower portion of atleast one of the one or more diode trenches with the dummy layer liner;and forming a second semiconductor segment in an upper portion of the atleast one of the one or more diode trenches with the first semiconductorsegment, where the second semiconductor segment is formed on the firstsemiconductor segment to form a p-n junction.

A method of forming a vertical finFET and a vertical diode device on thesame substrate includes forming a counter-doped layer on a substrate anda heavily doped layer on the counter-doped layer; forming a bottomspacer layer on the heavily doped layer; forming a dummy gate layer onthe bottom spacer layer; forming a top spacer layer on the dummy gatelayer; forming one or more fin trenches, where at least one of the oneor more fin trenches passes through the top spacer layer, the dummy gatelayer, and the bottom spacer layer; oxidizing at least a portion of theexposed portion of the dummy gate layer inside the one or more fintrenches to form a dummy layer liner; forming a vertical fin in at leastone of the one or more fin trenches with the dummy layer liner; formingone or more diode trenches, where at least one of the one or more diodetrenches passes through the top spacer layer, the dummy gate layer, andthe bottom spacer layer; oxidizing at least a portion of the exposedportion of the dummy gate layer inside the one or more diode trenches toform a dummy layer liner; forming a first semiconductor segment in alower portion of at least one of the one or more diode trenches with thedummy layer liner; and forming a second semiconductor segment in anupper portion of the at least one of the one or more diode trenches withthe first semiconductor segment, where the second semiconductor segmentis formed on the first semiconductor segment to form a p-n junction.

A vertical finFET and a vertical diode device on the same substrate,including a vertical fin formed on a heavily doped layer, where theheavily doped region forms a source/drain; a bottom spacer layer on theheavily doped layer and adjacent the sidewall of the vertical fin; ahigh-K dielectric layer on at least a portion of the sidewalls of thevertical fin; a work function layer on the high-K dielectric layer onthe portion of the sidewall of the vertical fin; a gate metal layer onat least a portion of the work function layer; a first semiconductorsegment on the heavily doped layer; and a second semiconductor segmenton the first semiconductor segment, where the interface between thesecond semiconductor segment and the first semiconductor segment is ap-n junction.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1, which is a cross-sectional side view of a substrate inaccordance with an exemplary embodiment;

FIG. 2 is a cross-sectional side view of a substrate with a bottomspacer layer, a dummy gate layer, a top spacer, and an oxide layer, on aheavily doped layer in accordance with an exemplary embodiment;

FIG. 3 is a cross-sectional side view of a trench from the oxide layerto the surface of the heavily doped layer in accordance with anexemplary embodiment;

FIG. 4 is a cross-sectional side view of a trench with the dummy gatelayer having an oxidized inner surface in accordance with an exemplaryembodiment;

FIG. 5 is a cross-sectional side view of a vertical fin formed in a fintrench on the substrate in accordance with an exemplary embodiment;

FIG. 6 is a cross-sectional side view of a hardmask on a top portion ofa vertical fin and oxide layer in accordance with an exemplaryembodiment;

FIG. 7 is a cross-sectional side view of a hardmask over a vertical fin,and a trench from the oxide layer to the surface of the heavily dopedlayer in accordance with an exemplary embodiment;

FIG. 8 is a cross-sectional side view of a vertical fin and a diodetrench with an oxidized inner surface in accordance with an exemplaryembodiment;

FIG. 9 is a cross-sectional side view of a vertical fin and a diodetrench with a first semiconductor segment in accordance with anexemplary embodiment;

FIG. 10 is a cross-sectional side view of a vertical fin and a diodetrench with a first semiconductor segment and a second semiconductorsegment in accordance with an exemplary embodiment;

FIG. 11 is a cross-sectional side view of a vertical fin, a verticaldiode, and an oxide layer having a flat surface in accordance with anexemplary embodiment;

FIG. 12 is a cross-sectional side view of a recessed vertical fin andsecond semiconductor segment in accordance with an exemplary embodiment;

FIG. 13 is a cross-sectional side view of a nitride fill in the trenchrecesses in accordance with an exemplary embodiment;

FIG. 14 is a cross-sectional side view of a nitride fill in accordancewith an exemplary embodiment;

FIG. 15 is a cross-sectional side view of a partially removed organicplanarization layer, nitride layer, and work function layer inaccordance with an exemplary embodiment;

FIG. 16 is a cross-sectional side view of a vertical fin with a thinnedportion and a second semiconductor segment with a thinned portion inaccordance with an exemplary embodiment;

FIG. 17 is a cross-sectional side view of a vertical fin with asource/drain and a second semiconductor segment with a anode/cathode inaccordance with an exemplary embodiment;

FIG. 18 is a cross-sectional side view of a spacer dielectric layer onthe nitride caps, source/drain, and anode/cathode in accordance with anexemplary embodiment;

FIG. 19 is a cross-sectional side view of a patterned spacer dielectriclayer over the caps, source/drain, and anode/cathode in accordance withan exemplary embodiment;

FIG. 20 is a cross-sectional side view of a portion of the top spacerlayer and a portion of the dummy gate layer removed in accordance withan exemplary embodiment;

FIG. 21 is a cross-sectional side view of the dummy gate layer removedfrom a vertical fin in accordance with an exemplary embodiment;

FIG. 22 is a cross-sectional side view of the dummy layer liners removedfrom the vertical fin and a soft mask over a vertical diode structure inaccordance with an exemplary embodiment;

FIG. 23 is a cross-sectional side view of a gate dielectric layer and awork function layer formed on the sides of a vertical fin in accordancewith an exemplary embodiment;

FIG. 24 is a cross-sectional side view of a vertical fin and gatestructure in accordance with an exemplary embodiment;

FIG. 25 is a cross-sectional side view of a vertical fin and gatestructure with a gate metal layer and gate electrode in accordance withan exemplary embodiment; and

FIG. 26 is a cross-sectional side view of a vertical field effecttransistor having a vertical fin, a gate structure with a gateelectrode, and a vertical diode, in accordance with an exemplaryembodiment.

DETAILED DESCRIPTION

Principles and embodiments of the present disclosure relate generally toa channel last fabrication approach to form a vertical field effecttransistor (VFET), or more specifically a vertical finFET, where currentflows vertically through the channel, and a vertical p-n diode on thesame substrate. The vertical finFET and vertical diode may beepitaxially grown on a coterminous region of a substrate surfaceimplementing various fabrication processes.

Principles and embodiments also relate to forming one or more verticalfin field effect transistor (vertical finFETs) and one or more verticaldiodes, wherein at least a portion of the vertical diode and the channelportion of the finFET(s) are epitaxially grown from the same substratesurface. The one or more vertical fin(s) and one or more verticaldiode(s) may be formed in trenches etched into the same channel layerstack on a substrate.

It is to be understood that the present invention will be described interms of a given illustrative architecture; however, otherarchitectures, structures, substrate materials and process features andsteps may be varied within the scope of the present invention.

It will also be understood that when an element such as a layer, regionor substrate is referred to as being “on” or “over” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

The present embodiments may include a design for an integrated circuitchip, which may be created in a graphical computer programming language,and stored in a computer storage medium (such as a disk, tape, physicalhard drive, or virtual hard drive such as in a storage access network).If the designer does not fabricate chips or the photolithographic masksused to fabricate chips, the designer may transmit the resulting designby physical means (e.g., by providing a copy of the storage mediumstoring the design) or electronically (e.g., through the Internet) tosuch entities, directly or indirectly. The stored design is thenconverted into the appropriate format (e.g., GDSII) for the fabricationof photolithographic masks, which typically include multiple copies ofthe chip design in question that are to be formed on a wafer. Thephotolithographic masks are utilized to define areas of the wafer(and/or the layers thereon) to be etched or otherwise processed.

Methods as described herein may be used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe one element's or feature's relationship to another element(s)or feature(s) as illustrated in the FIGs. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the FIGs. For example, if the device in theFIGs. is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations), and the spatially relativedescriptors used herein may be interpreted accordingly. In addition, itwill also be understood that when a layer is referred to as being“between” two layers, it can be the only layer between the two layers,or one or more intervening layers may also be present.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another element. Thus, a first element discussed belowcould be termed a second element without departing from the scope of thepresent concept.

While exemplary embodiments have been shown for a particular device, itshould be understood that a plurality of such devices may be arrangedand/or fabricated on a substrate to form integrated devices that may beintegrated onto a substrate, for example through very large scaleintegration to produce complex devices such a central processing units(CPUs) and application specific integrated circuits (ASICs). The presentembodiments may be part of a device or circuit, and the circuits asdescribed herein may be part of a design for an integrated circuit chip.

Referring now to the drawings in which like numerals represent the sameor similar elements and initially to FIG. 1, which is a cross-sectionalside view of a substrate in accordance with an exemplary embodiment.

In one or more embodiments, a substrate 110 may be a semiconductor. Thesubstrate may be crystalline. The substrate may be essentially (i.e.,except for contaminants) a single element (e.g., silicon), primarily ofa single element (i.e., with doping), for example, silicon (Si) orgermanium (Ge), or the substrate may be a compound semiconductor, forexample, a III-V compound semiconductor (e.g., GaAs), SiC, or SiGe. Thesubstrate may also have multiple material layers, for example, asemiconductor-on-insulator substrate (SeOI), a silicon-on-insulatorsubstrate (SOI), germanium-on-insulator substrate (GeOI), orsilicon-germanium-on-insulator substrate (SGOI). In one or moreembodiments, the substrate 110 may be a silicon wafer. In variousembodiments, the substrate is a single crystal silicon wafer. A singlecrystal silicon substrate may have a <100> or a <111> surface, which maybe used for epitaxial growth of a FET channel and/or a diode.

In one or more embodiments, a counter-doped layer 120 may be formed onor within the substrate 110, where the counter-doped layer 120 may beused to electrically isolate a source/drain region from the bulk of asubstrate. The counter-doped layer 120 may be n-doped or p-doped.

In one or more embodiments, a heavily doped layer 130 may be formed onthe counter-doped layer 120. The heavily doped layer 130 may be n-dopedor p-doped. The heavily doped layer 130 may have a dopant concentrationin the range of about 1×10¹⁹ to about 1×10²² dopant atoms/cm³. Invarious embodiments, the heavily doped layer 130 may form a source or adrain of a finFET, and/or an anode/cathode of a diode. It should benoted that a source and a drain may be interchanged, where the drain maybe in the substrate below a vertical fin and the source may be formed onthe top of a vertical fin. An anode and cathode of a diode may beinterchanged based on the doping of the diode segments.

In one or more embodiments, the counter-doped layer 120 and the heavilydoped layer 130 may each be in-situ doped during epitaxial growth on asingle crystal substrate. In various embodiments, dopants may be ionimplanted into the counter-doped layer 120 and/or the heavily dopedlayer 130. The counter-doped layer 120 may include dopants of anopposite type relative to the heavily doped layer 130 to provide adepletion layer at the interface of the counter-doped layer 120 and theheavily doped layer 130.

FIG. 2 is a cross-sectional side view of a substrate with a bottomspacer layer, a dummy gate layer, a top spacer layer, and an oxidelayer, on a heavily doped layer in accordance with an exemplaryembodiment.

In one or more embodiments, a bottom spacer layer 140 may be formed on aexposed surface of the substrate heavily doped layer 130. The bottomspacer layer 140 may be a dielectric material other than a high-Kdielectric, for example, silicon oxide (SiO), silicon nitride (SiN), orboron nitride (BN). The bottom spacer layer 140 may be deposited bychemical vapor deposition (CVD), physical layer deposition (PVD), atomiclayer deposition (ALD), as well as modifications thereof, such as plasmaenhanced (e.g., PECVD), metal organic (e.g., MOCVD), electron beam(e.g., EB-PVD), low pressure (e.g., LPCVD), etc., or combinationsthereof. The bottom spacer layer 140 may act as an etch stop layerduring fabrication processes.

In one or more embodiments, the bottom spacer layer 140 may have athickness in the range of about 2 nm to about 10 nm, or in the range ofabout 2 nm to about 5 nm. The thickness of the bottom spacer layer 140may define the distance of a bottom edge of a gate structure from theheavily doped layer 130.

In various embodiments, a trench may be formed in the bottom spacerlayer 140, heavily doped layer 130, and through the counter-doped layer120 into a portion of the substrate 110. The trench may be filled with adielectric, insulating material to provide shallow trench isolation(STI) regions 180 between neighboring regions of the heavily doped layer130. The STI region 180 may electrically isolate different regions ofthe heavily doped layer 130 that may form bottom source/drain regions ofa vertical finFET and/or bottom anode/cathode regions of a verticaldiode. In various embodiments, the trench is filled with silicon oxide(SiO) to form the STI region 180. The SiO fill of the STI region 180 andthe bottom spacer layer 140 may be chemically-mechanically polishedprior to the formation of subsequent layers on the bottom spacer layer140 to provide a uniform flat surface.

In one or more embodiments, a dummy gate layer 150 may be formed on thebottom spacer layer 140 and a STI region 180, which may provide asacrificial template for forming a vertical channel, a gate structure ona channel, and/or a diode structure. In various embodiments, the dummygate layer 150 may be amorphous silicon (a-Si) or polycrystallinesilicon (p-Si).

In one or more embodiments, the dummy gate layer 150 may have athickness in the range of about 10 nm to about 100 nm, or in the rangeof about 10 nm to about 50 nm, or in the range of about 10 nm to about20 nm.

In one or more embodiments, a top spacer layer 160 may be formed on thedummy gate layer 150, where the top spacer layer 160 may be the samematerial as the bottom spacer layer 140. The top spacer layer 160 may bea dielectric material other than a high-K metal oxide dielectric, forexample, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride(SiON), or boron nitride (BN).

In one or more embodiments, the top spacer layer 160 may have athickness in the range of about 2 nm to about 10 nm, or in the range ofabout 2 nm to about 5 nm. The top spacer layer 160 may have a differentthickness than the bottom spacer layer 140.

The bottom spacer layer 140, dummy gate layer 150, and top spacer layer160 may form a channel layer stack 199, where the channel layer stackmay provide a template for defining a vertical channel and/or forming agate structure.

In one or more embodiments, an oxide layer 170 may be formed on the topspacer layer 160, where the oxide layer 170 may be a sacrificial layerblanket deposited on the top spacer layer 160. The oxide layer 170 maybe silicon oxide (SiO), which may be formed by a CVD deposition or a PVDdeposition. The oxide layer 170 may be a different material than the topspacer layer 160, such that the top spacer layer 160 may act as an etchstop layer.

FIG. 3 is a cross-sectional side view of a trench from the oxide layerto the surface of the heavily doped layer in accordance with anexemplary embodiment.

In various embodiments, a photo mask layer may be a temporary resist(e.g., PMMA) that may be deposited on the oxide layer 170, patterned,and developed. The photo mask layer may be a positive resist or anegative resist. One or more openings may be patterned in the photo masklayer for forming one or more fin trenches 175 through the oxide layer170 and in the channel layer stack 199. The size and placement of theopenings in the photo mask layer may define the width, length, and pitchof the one or more openings, and thereby, the width, length, and pitchof the one or more vertical fins.

In one or more embodiments, one or more suitable etching processes maybe utilized to remove material from the oxide layer 170, top spacerlayer 160, dummy gate layer 150, and bottom spacer layer 140, to form afin trench 175, where the underlying material may act as an etch stoplayer for each of the one or more etching processes sequentiallyutilized to form the fin trench(es) 175. In various embodiments, the fintrenches 175 may be etched using a directional reactive ion etching(RIE) process.

In one or more embodiments, the openings in the photo mask layer mayhave a width in the range of about 6 nm to about 20 nm, or may have awidth in the range of about 8 nm to about 15 nm, or may have a width inthe range of about 10 nm to about 12 nm. The trenches 175 may have awidth in the range of about 6 nm to about 20 nm, or may have a width inthe range of about 8 nm to about 15 nm, or may have a width in the rangeof about 10 nm to about 12 nm, and a depth in the range of about 30 nmto about 300 nm, or a depth in the range of about 50 nm to about 150 nm.

FIG. 4 is a cross-sectional side view of a trench with the dummy gatelayer having an oxidized inner surface in accordance with an exemplaryembodiment.

In one or more embodiments, after formation of the one or more fintrench(es) 175, at least a portion of the channel layer stack 199 insidethe one or more fin trenches 175 may be oxidized to form a dummy layerliner 190. In various embodiments, the oxide layer 170, top spacer layer160, dummy gate layer 150, and bottom spacer layer 140 may be exposed tooxidation, where the exposed portion of the dummy gate layer 150 insidethe fin trench 175 may be oxidized to form a dummy layer liner 190. Thedummy layer liner 190 may surround the trench 175 at the level of thedummy gate layer. The dummy layer liner may protect the interfacebetween the vertical fin and the dummy gate layer during epitaxialgrowth and/or subsequent processes, where the dummy layer liner mayavoid an amorphous crystal structure of the dummy gate layer interferingwith the epitaxial growth.

In various embodiments, the dummy layer liner 190 may be formed byplasma oxidation or thermal oxidation of the sidewalls of the dummy gatelayer 150 within the fin trench 175. In various embodiments, thermaloxidation may be done using an oxidizing gas (e.g., O₂, O₃, etc.) attemperatures in the range of about 600° C. to about 1200° C. Theoxidation of the dummy gate layer material (e.g., a-Si) may form SiO₂.

In various embodiments, the sidewalls of the dummy gate layer 150 withinthe fin trenches 175 may be oxidized after extending the fin trenches175 through the bottom spacer layer 140 to the surface of the heavilydoped layer 130. In various embodiments, a trench may be etched all theway down to the heavily doped layer, then an oxide layer may be grown onthe exposed surface of the dummy gate layer 150 inside the trench by aplasma oxidation, where the oxide grows selectively only on the dummygate layer material to form a dummy layer liner 190.

FIG. 5 is a cross-sectional side view of a vertical fin formed in a fintrench on the substrate in accordance with an exemplary embodiment.

In one or more embodiments, a vertical fin 200 may be formed within eachof the one or more fin trenches 175 formed in the oxide layer 170 andchannel layer stack 199. The one or more vertical fins 200 may be formedby epitaxial growth from the exposed surface of the heavily doped layer130. In various embodiments, the heavily doped layer 130 may have a<100> or <111> crystal orientation, and the vertical fins 200 may beformed with the same crystal orientation as the heavily doped layer 130.The heavily doped layer 130 may have the same crystal orientation as thebulk substrate or an active layer on an SeOI substrate. In variousembodiments, the top surface of the vertical fins 200 may have a <100>crystal orientation. By forming the vertical fin(s) 200 on the heavilydoped layer 130, the source-channel junction is self-aligned at thecommon interface.

In various embodiments, the one or more vertical fins 200 are formed onthe heavily doped layer 130, where regions of the heavily doped layermay be isolated by STI region 180, wherein the heavily doped region inthe substrate may act as a source or a drain for a VFET, and thevertical fins 200 act as a channel for the VFET.

In one or more embodiments, the vertical fins 200 may be silicon, (Si),germanium (Ge), silicon-germanium (SiGe), gallium arsenide (GaAs),indium gallium arsenide (InGaAs), indium arsenide (InAs), or indiumaluminum arsenide (InAlAs). The vertical fins 200 may be single crystalepitaxially grown on the heavily doped layer 130. The vertical fins 200may extend above the surface of the oxide layer 170 and expand laterallydue to different growth rates of the different crystal faces.

In one or more embodiments, the one or more vertical fins 200 may have awidth in the range of about 6 nm to about 20 nm, or may have a width inthe range of about 8 nm to about 15 nm, or may have a width in the rangeof about 10 nm to about 12 nm, and a length in the range of about 30 nmto about 300 nm, or about 50 nm to about 150 nm.

FIG. 6 is a cross-sectional side view of a hardmask on a top portion ofa vertical fin and oxide layer in accordance with an exemplaryembodiment.

In one or more embodiments, a hardmask 205 may be formed over at leastthe exposed portion of one or more vertical fins 200, where the hardmask205 may cover a portion of the top surface of the oxide layer 170. Thehardmask 205 may be formed on the portion of the vertical fin(s) 200extending above the surface of the oxide layer 170, and may cover aportion of the oxide layer 170 surrounding the portion of the verticalfin(s) 200. The hardmask 205 may be selectively formed on the exposedportion of one or more vertical fins 200, while portions of the oxidelayer 170 remain exposed for forming additional trenches for formationof one or more diode structures. In various embodiments, the hardmaskmay be silicon nitride.

FIG. 7 is a cross-sectional side view of a hardmask over a vertical fin,and a trench from the oxide layer to the surface of the heavily dopedlayer in accordance with an exemplary embodiment.

In one or more embodiments, the hardmask 205 covers a portion of theoxide layer 170, and a diode trench 176 may be formed through theexposed surface of the oxide layer 170. A photomask layer may be formedand patterned on the exposed portion of the oxide layer 170. One or moreopenings may be patterned in the photo mask layer for forming one ormore diode trenches 176 through the oxide layer 170 and in the channellayer stack 199. The size and placement of the openings in the photomask layer may define the width, length, and pitch of the one or moreopenings, and thereby, the width, length, and pitch of the one or morediode structures.

In one or more embodiments, one or more suitable etching processes maybe utilized to remove material from the oxide layer 170, top spacerlayer 160, dummy gate layer 150, and bottom spacer layer 140, to form adiode trench 176, where the underlying material may act as an etch stoplayer for each of the one or more etching processes sequentiallyutilized to form the fin trench(es) 175. In various embodiments, the fintrenches 175 may be etched using a directional reactive ion etching(RIE) process.

FIG. 8 is a cross-sectional side view of a vertical fin and a diodetrench with an oxide liner in accordance with an exemplary embodiment.

In one or more embodiments, after formation of the one or more diodetrench(es) 176, at least a portion of the channel layer stack 199 insidethe one or more diode trenches 176 may be oxidized to form a dummy layerliner 190. In various embodiments, the oxide layer 170, top spacer layer160, dummy gate layer 150, and bottom spacer layer 140 may be exposed tooxidation, where the exposed portion of the dummy gate layer 150 may beoxidized to form a dummy layer liner 190. The dummy layer liner 190 maysurround the trench 175.

In various embodiments, the dummy layer liner 190 may be formed byplasma oxidation or thermal oxidation of the sidewalls of the dummy gatelayer 150 within the diode trench 176. In various embodiments, thermaloxidation may be done using an oxidizing gas (e.g., O₂, O₃, etc.) attemperatures in the range of about 600° C. to about 1200° C. Theoxidation of the dummy gate layer material (e.g., a-Si) may form SiO₂.

FIG. 9 is a cross-sectional side view of a vertical fin and a diodetrench with a first semiconductor segment in accordance with anexemplary embodiment.

In one or more embodiments, first semiconductor segment 210 may beformed in a lower portion of diode trench of each of the one or morediode trenches 176 formed in the oxide layer 170 and channel layer stack199. The one or more first semiconductor segment(s) 210 may be formed byepitaxial growth from the exposed surface of the heavily doped layer130. In various embodiments, the heavily doped layer 130 may have a<100> or <111> crystal orientation, and the first semiconductor segments210 may be formed with the same crystal orientation as the heavily dopedlayer 130. The heavily doped layer 130 may have the same crystalorientation as the bulk substrate or an active layer on an SeOIsubstrate. The heavily doped layer 130 may form a bottom anode/cathodefor the first semiconductor segment 210. In various embodiments, the topsurface of the first semiconductor segment 210 may have a <100> crystalorientation. By forming the first semiconductor segment 210 on theheavily doped layer 130, the junction is self-aligned at the commoninterface.

In one or more embodiments, the first semiconductor segment 210 may haveheight less than the depth of the diode trench 176, such that the top ofthe first semiconductor segment 210 may be below the bottom surface ofthe top spacer layer 160. In various embodiments, the firstsemiconductor segment 210 may be epitaxially gown to a height in therange of about one third to about two-thirds of the dummy gate layerthickness, or to a height approximately to the midpoint of the dummygate layer 150.

In one or more embodiments, first semiconductor segment 210 may be ann-doped or p-doped semiconductor, where the first semiconductor segment210 has the same doping as the heavily doped layer 130. Having the firstsemiconductor segment 210 with the same doping as the heavily dopedlayer 130 may avoid creating a junction or non-ohmic contact between theheavily doped layer 130 and the first semiconductor segment 210. Thesecond semiconductor segment 220 may be an n-doped or p-dopedsemiconductor, where the second semiconductor segment 220 has theopposite doping as the first semiconductor segment 210 to form a p-njunction for a vertical diode. In various embodiments, the secondsemiconductor segment 220 has the opposite doping as the heavily dopedlayer 130.

FIG. 10 is a cross-sectional side view of a vertical fin and a diodetrench with a first semiconductor segment and a second semiconductorsegment in accordance with an exemplary embodiment.

In one or more embodiments, a second semiconductor segment 220 may beformed in an upper portion of each of the one or more diode trenches 176formed in the oxide layer 170 and channel layer stack 199. The secondsemiconductor segment 220 may be formed on the top surface of the firstsecond semiconductor segment 210, where the second semiconductor segment220 may be formed by epitaxial growth on the first semiconductor segment210. The second semiconductor segment 220 may be formed with the samecrystal orientation as the first semiconductor segments 210. In variousembodiments, the top surface of the second semiconductor segment 220 mayhave a <100> crystal orientation.

The second semiconductor segment 220 may extend above the surface of theoxide layer 170, and expand laterally due to different growth rates ofthe crystal faces.

In one or more embodiments, the first semiconductor segments 210 andsecond semiconductor segments 220 may have a width in the range of about6 nm to about 20 nm, or may have a width in the range of about 8 nm toabout 15 nm, or may have a width in the range of about 10 nm to about 12nm, and a combined height in the range of about 30 nm to about 300 nm,or a height in the range of about 50 nm to about 150 nm.

In one or more embodiments, the first semiconductor segment 210 andsecond semiconductor segment 220 in the same diode trench form a p-njunctions at the interface of the first semiconductor segment 210 andsecond semiconductor segment 220. The first semiconductor segment 210and second semiconductor segment 220 may form a diode in each of the oneor more diode trenches 176.

FIG. 11 is a cross-sectional side view of a vertical fin, a verticaldiode, and an oxide layer having a flat surface in accordance with anexemplary embodiment.

In one or more embodiments, a portion of the oxide layer 170 and theportions of the vertical fin(s) 200 and second semiconductor segments220 extending above the top surface of the oxide layer 170 may beremoved to provide a uniform flat surface. In various embodiments, theportions of the vertical fin(s) 200 and second semiconductor segments220 extending above the top surface of the oxide layer 170, as well as aportion of the oxide layer 170, may be removed by CMP.

FIG. 12 is a cross-sectional side view of a recessed vertical fin andsecond semiconductor segment in accordance with an exemplary embodiment.

In one or more embodiments, a fraction of a vertical fin 200 and/orsecond semiconductor segment 220 may be removed from an upper portion offin trench 175 and/or diode trench 176 respectively to form recess(es)178. In various embodiments, the height of the vertical fin 200 may bereduced, such that the top surface of the vertical fin 200 is below thetop surface of the oxide layer 170 but above the top surface of the topspacer layer 160. In various embodiments, the height of the secondsemiconductor segment 220 may be reduced, such that the top surface ofthe second semiconductor segment 220 is below the top surface of theoxide layer 170 but above the top surface of the top spacer layer 160.

In various embodiments, the fraction of a vertical fin 200 and/or secondsemiconductor segment 220 may be removed by a selective etch, where theselective etch may be a wet etch or a blanket RIE.

FIG. 13 is a cross-sectional side view of a nitride fill in the trenchrecesses in accordance with an exemplary embodiment.

In one or more embodiments, a nitride fill 230 may be formed in at leastthe one or more recesses 178 formed in the trenches, where the nitridefill may be silicon nitride. The nitride fill may extend above the topof the recesses and form at least a partial layer over oxide layer 170.

FIG. 14 is a cross-sectional side view of a nitride fill in accordancewith an exemplary embodiment.

In one or more embodiments, after formation of the nitride fill 230, theportion of the nitride fill extending above the top surface of the oxidelayer 170 may be removed, where the nitride fill 230 may be removed byCMP.

FIG. 15 is a cross-sectional side view of a partially removed organicplanarization layer, nitride layer, and work function layer inaccordance with an exemplary embodiment.

In one or more embodiments, the oxide layer 170 above the top spacerlayer 160 may be selectively removed to expose at least an upper portionof a vertical fin and at least an upper portion of a secondsemiconductor segment. The nitride caps 235, 236 may also be exposed byremoval of the oxide layer 170. In various embodiments, the oxide layermay be removed by a wet etch and/or a blanket RIE.

FIG. 16 is a cross-sectional side view of a vertical fin with a thinnedportion and a second semiconductor segment with a thinned portion inaccordance with an exemplary embodiment.

In one or more embodiments, the width of an upper portion of the one ormore vertical fin(s) 200, approximately between the nitride cap 235 andthe top spacer layer 160, may be reduced by selective etching ofparticular crystal faces of the one or more vertical fin(s) 200. Atleast an upper portion of the one or more vertical fin(s) 200 maythereby be thinned.

In various embodiments, etching the sides of an upper portion of avertical fin 200 may also remove vertical fin material below the topsurface of the top spacer layer 160.

In one or more embodiments, the width of the one or more secondsemiconductor segment(s) 220 approximately between the nitride cap 235and the top spacer layer 160 may be reduced by selective etching ofparticular crystal faces of the one or more second semiconductorsegment(s) 220. At least an upper portion of the one or more secondsemiconductor segment(s) 220 may thereby be thinned.

In various embodiments, etching the sides of an upper portion of asecond semiconductor segment 220 may also remove second semiconductorsegment material below the top surface of the top spacer layer 160. Thesecond semiconductor segment 220 may extend from the p-n junction withthe first semiconductor segment 210 to the nitride cap above the topsurface of the top spacer layer 160.

In one or more embodiments, the thinned portion of the vertical fin(s)200 may have a width in the range of about 2 nm to about 3 nm. In one ormore embodiments, the thinned portion of the second semiconductorsegment(s) 220 may have a width in the range of about 2 nm to about 3nm. The nitride caps 235, 236 may be supported on the tops of thethinned portions of the vertical fin(s) 200 and/or second semiconductorsegment(s) 220.

FIG. 17 is a cross-sectional side view of a vertical fin with asource/drain and a second semiconductor segment with an anode/cathode inaccordance with an exemplary embodiment.

In one or more embodiments, a doped material forming a top source/drain225 may be formed on the one or more vertical fin(s) 200. The topsource/drain 225 may be formed by epitaxial growth on the exposedsurface of the thinned portion of the vertical fin(s) 200, such that thevertical fin 200 and the top source/drain 225 have the same crystalorientation. The top source/drain 225 may be n-doped or p-doped. The topsource/drain may be doped in-situ during deposition of the topsource/drain 225.

In one or more embodiments, a doped material forming a top anode/cathode226 may be formed on the one or more second semiconductor segment(s)220. The top anode/cathode 226 may be formed by epitaxial growth on theexposed surface of the thinned portion of the second semiconductorsegment(s) 220, such that the second semiconductor segment(s) 220 andthe top anode/cathode 226 have the same crystal orientation. The topanode/cathode 226 may be n-doped or p-doped. The top anode/cathode maybe doped in-situ during deposition of the top anode/cathode 226.

In various embodiments, the locations of the source and drain of avertical transistor may be reversed such that the drain is on the top ofa vertical fin, while the source is at the bottom. The source may,therefore, be at the bottom or the top.

FIG. 18 is a cross-sectional side view of a spacer dielectric layer onthe nitride caps and source/drains in accordance with an exemplaryembodiment.

In various embodiments, a dielectric material 240, for example, siliconoxide (e.g., SiO₂), may be formed on the top spacer layer 160 and coverthe nitride caps 235 and the source/drains 225 on the vertical fin(s)200, and the nitride caps 236 and anode/cathode 226 on the secondsemiconductor segment(s) 220 respectively. The dielectric material 240may be blanket deposited over the nitride caps 235, 236 thesource/drains 225, and anode/cathodes 226. In various embodiments, theheight of the dielectric material 240 may be reduced bychemical-mechanical polishing (CMP) and/or etching.

FIG. 19 is a cross-sectional side view of a patterned dielectric layerover the nitride caps and source/drains in accordance with an exemplaryembodiment.

In one or more embodiments, the dielectric material 240 may be patternedand portions removed to expose portions of the underlying top spacerlayer 160. The dielectric material 240 may act as a hardmask forremoving portions of the top spacer layer 160 and the dummy gate layer150.

FIG. 20 is a cross-sectional side view of a portion of the top spacerlayer and a portion of the dummy gate layer removed in accordance withan exemplary embodiment.

In one or more embodiments, a portion of the top spacer layer 160 and aportion of the dummy gate layer 150 may be removed. The top spacer layer160 and the dummy gate layer 150 may be removed by a directional RIE.

FIG. 21 is a cross-sectional side view of the dummy gate layer removedfrom a vertical fin in accordance with an exemplary embodiment.

In one or more embodiments, the remaining portion of the dummy gatelayer 150 shadowed by the patterned dielectric material 240 andremaining portion of the top spacer layer 160 may be removed to exposethe dummy layer liners 190 on the vertical fins 200, and on the firstsemiconductor segments 210 and second semiconductor segments 220 of avertical diode 500. The remaining portion of the dummy gate layer 150may be removed by a wet chemical etch

FIG. 22 is a cross-sectional side view of the dummy layer liners removedfrom the vertical fin and a soft mask over a vertical diode structure inaccordance with an exemplary embodiment.

In one or more embodiments, the dummy layer liners 190 on the verticalfins 200 may be removed by a wet etch or RIE, where the wet etch or RIEmay selectively remove silicon oxide.

In various embodiments, the vertical fins 200 may have height in therange of about 14 nm to about 120 nm, or in the range of about 16 nm toabout 110 nm, or in the range of about 20 nm to about 30 nm, where theheight is measured from the heavily doped source 130 to the bottom ofthe source/drain 225.

In one or more embodiments, a soft mask 290 may be formed on the diodestructure to protect the diode structure during the removal of the dummylayer liners 190 and formation of gate dielectric layers, work functionlayers, and gate metal layers.

FIG. 23 is a cross-sectional side view of a gate dielectric layer and awork function layer formed on the sides of a vertical fin in accordancewith an exemplary embodiment.

In one or more embodiments, a gate dielectric layer 250 may be formed onthe vertical fin 200, bottom spacer layer 140, and dielectric material240, where the gate dielectric layer 250 may be conformally deposited.The gate dielectric layer 250 may be conformally deposited by ALD and/orCVD.

In various embodiments, the gate dielectric layer 250 may be a high-Kmaterial, including but is not limited to metal oxides such as hafniumoxide (e.g., HfO₂), hafnium silicon oxide (e.g., HfSiO₄), hafniumsilicon oxynitride (Hf_(w)Si_(x)O_(y)N_(z)), lanthanum oxide (e.g.,La₂O₃), lanthanum aluminum oxide (e.g., LaAlO₃), zirconium oxide (e.g.,ZrO₂), zirconium silicon oxide (e.g., ZrSiO₄), zirconium siliconoxynitride (Zr_(w)Si_(x)O_(y)N_(z)), tantalum oxide (e.g., TaO₂, Ta₂O₅),titanium oxide (e.g., TiO₂), barium strontium titanium oxide (e.g.,BaTiO₃—SrTiO₃), barium titanium oxide (e.g., BaTiO₃), strontium titaniumoxide (e.g., SrTiO₃), yttrium oxide (e.g., Y₂O₃), aluminum oxide (e.g.,Al₂O₃), lead scandium tantalum oxide (Pb(Sc_(x)Ta_(1-x))O₃), and leadzinc niobate (e.g., PbZn_(1/3)Nb_(2/3)O₃). The high-k dielectricmaterial may further include dopants such as lanthanum and/or aluminum.The stoichiometry of the high-K dielectric material may vary.

In various embodiments, the gate dielectric layer 250 may have athickness in the range of about 1.5 nm to about 2.5 nm.

In one or more embodiments, a work function layer 260 may be depositedover the gate dielectric layer 250, where the work function layer 260may be conformally deposited by ALD and/or CVD.

In various embodiments, the work function layer 260 may be a nitride,including but not limited to titanium nitride (TiN), hafnium nitride(HfN), hafnium silicon nitride (HfSiN), tantalum nitride (TaN), tantalumsilicon nitride (TaSiN), tungsten nitride (WN), molybdenum nitride(MoN), niobium nitride (NbN); a carbide, including but not limited totitanium carbide (TiC), tantalum carbide (TaC), hafnium carbide (HfC),and combinations thereof.

In various embodiments, the work function layer 260 may have a thicknessin the range of about 1 nm to about 11 nm, or may have a thickness inthe range of about 2 nm to about 5 nm.

In one or more embodiments, a gate metal layer 265 may be formed on thework function layer 160, where the gate metal layer 265 may include athin layer conformally deposited on the work function layer 260, and/ora metal fill 270 to form a gate electrode. The gate metal layer 265 maybe conformally deposited by atomic layer deposition (ALD) or CVD, wherethe gate metal layer 265 may have a thickness in the range of about 5 Åto about 15 Å.

In various embodiments, the gate metal layer 265 may be tungsten (W),aluminum (Al), titanium nitride (TiN), cobalt (Co), or a combinationthereof. The total thickness of the gate metal layer 265 and the workfunction layer 260 may be in the range of about 6 nm to about 12 nm.

In various embodiments, the gate dielectric layer 250 and bottom spacerlayer 140 remain on the heavily doped layer 130, and may provideelectrical insulation between the heavily doped layer 130 and the gatemetal layer 265 and/or metal fill 270. Unneeded metal(s) (gate metallayer 265, work function layer 260, and metal fill 270) may be etchedaway. The gate metal layer 265 and underlying work function layer 260may be removed to avoid electrically shorting the fabricated componentson the substrate (e.g., wafer).

Portions of the high-K layer 250 may also be removed in defining thegate structure for each vertical fin 200. In various embodiments, thehigh-K layer 250, the gate metal layer 265, and work function layer 260may form a gate structure at least on opposite sides of the vertical fin200. In various embodiments, the gate structure may wrap around threesides or four sides of the vertical fin.

FIG. 24 is a cross-sectional side view of a vertical fin and gatestructure in accordance with an exemplary embodiment.

In one or more embodiments, the gate dielectric layer 250, work functionlayer 260 and the gate metal layer 265 may be removed from at least aportion of the bottom spacer layer 140 of the one or more vertical fins200 to form a gate structure on the vertical fins 200. In variousembodiments, each layer may be removed by a suitable directional etchingprocess (e.g., RIE), where the underlying layer may act as an etch stoplayer.

FIG. 25 is a cross-sectional side view of a vertical fin and gatestructure with a gate metal layer and gate electrode in accordance withan exemplary embodiment.

In one or more embodiments, a gate metal fill 270 may be deposited onthe gate metal layer 265. In one or more embodiments, a gate metal fill270 may be tungsten (W). The gate metal fill 270 may provide anelectrical contact with the gate metal layer 265 of the gate structurefor back end of line (BEOL) electrical connections.

In various embodiments, the gate metal fill 270 may extend laterallybeyond the dielectric material 240 to allow formation of metal contactto the gate structure. The gate metal fill 270 may be electricallyisolated from the heavily doped layer 130 by bottom spacer layer 140.

FIG. 26 is a cross-sectional side view of a vertical field effecttransistor having a vertical fin, a gate structure with a gateelectrode, and a vertical diode, in accordance with an exemplaryembodiment.

In one or more embodiments, the space above the metal fill 270 may befilled with a dielectric fill 300 to fill in the space betweenneighboring structures, including vertical fins 200 and vertical diodes,and provide electrical insulation between devices and components. Invarious embodiments, the soft mask 290 may be removed from the diodestructure prior to forming the dielectric fill 300. In variousembodiments, the soft mask 290 may remain on the diode structure, whilethe dielectric fill 300 is formed on the finFET structure, and the softmask 290 removed and dielectric fill 300 formed on the diode structurein a separate stage. The middle-of-line contacts may be formed, wherethe gate, source and drain contacts may be made to the transistorcomponents, and the anode/cathode contacts may be made to the diodeusing any well-known process for making contacts.

One or more trenches may be formed in the dielectric fill 300, soft mask290, and/or dielectric material 240 by masking, patterning, and etching.The trench(es) may extend vertically down through the dielectric fill300 to the metal fill 270 to form metal contacts for back end of line(BEOL) electrical connections to the gate structure(s).

In various embodiments, trenches may be etched vertically down throughthe dielectric material 240 to the top source/drain 225 to form metalcontacts to the vertical finFET. The nitride cap 235 may be removed toallow access to the top surface of the top source/drain 225.

In various embodiments, trenches may be etched vertically down throughthe dielectric material 240 and soft mask 290 to the top anode/cathode226 to form metal contacts to the vertical diode. The nitride cap 236may be removed to allow access to the top surface of the topanode/cathode 226.

In various embodiments, the trench(es) may be filled with a barrierlayer 285 and/or a metal contact fill 280. A barrier layer 285 may beselectively formed in trench(es) formed in the dielectric material 240to the top source/drain 225, anode/cathode 226, and/or the top of thesecond semiconductor segment 220. In various embodiments, a metalcontact fill 280 may be the same material as the metal fill 270, and maybe formed in trenches to the metal fill 270 without an interveningbarrier layer 285. In various embodiments, the metal contact fill 280may be a different material from the metal fill 270, and an interveningbarrier layer 285 may be formed between the metal contact fill 280 andthe metal fill 270 to avoid alloying and/or diffusion.

In one or more embodiments, a metal contact fill 280 may be tungsten(W), aluminum (Al), or copper (Cu). In various embodiments, the barrierlayer 285 may be titanium nitride (TiN), tantalum nitride (TaN), hafniumnitride (HfN), niobium nitride (NbN), tungsten nitride (WN), orcombinations thereof, where the barrier layer may prevent diffusionand/or alloying of the metal contact fill material with the top sourcedrain material, anode/cathode material, and/or metal fill 270. Invarious embodiments, the barrier layer may be conformally deposited inthe trench(es) by ALD, CVD, MOCVD, PECVD, or combinations thereof. Invarious embodiments, the metal fill 270 may be formed by ALD, CVD,and/or PVD to form the electrical contacts.

In various embodiments, the top surfaces of the metal contact fill 280,dielectric fill 300, and/or dielectric material 240 may bechemically-mechanically polished to provide a uniform surface.

In one or more embodiments, a vertical finFET and vertical diode devicemay include a bulk substrate 110, a heavily doped layer 130, a shallowtrench isolation region 180 dividing the heavily doped layer 130 into aplurality of heavily doped regions in the substrate to form a pluralityof electrically separate bottom source/drains and bottom anode/cathodes,a counter-doped layer 120 beneath the heavily doped layer 130 to provideelectrical isolation of the one or more heavily doped regions from thebulk substrate 110.

A vertical finFET 400 may include a vertical fin 200 formed on a bottomsource/drain, a bottom spacer layer 140, where the bottom spacer layermay electrically insulate the bottom source/drain from components of agate structure and/or metal fill 270. In various embodiments, the gatestructure may include a high-K dielectric layer 250, a work functionlayer 260, and a gate metal layer 265. A metal fill 270 may be depositedin contact with the gate metal layer 265 to provide electrical contactsto the finFET gate structure.

The vertical finFET 400 may include a top source/drain 225 on the top ofthe vertical fin(s) 200, where the vertical fin(s) 200 form a verticalchannel of a vertical finFET. The top source drain, bottom source/drain,and vertical fin form at least a portion of a vertical finFET. Invarious embodiments, the top source/drain and bottom source/drain may ben-doped or p-doped. The top source/drain and bottom source/drain alsomay be interchanged.

In one or more embodiments, the vertical diode 500 may include a firstsemiconductor segment 210 formed on a heavily doped region, a secondsemiconductor segment 220 formed on the first semiconductor segment 210,and a top anode/cathode 226 formed on the second semiconductor segment220. The first semiconductor segment 210 and the a second semiconductorsegment 220 may form a vertical diode, where the interface of the firstsemiconductor segment 210 and the a second semiconductor segment 220 maybe a diode p-n junction.

In one or more embodiments, the vertical finFET and vertical diodedevice 100 includes a vertical diode 500 fabricated on the samesubstrate 110 as the vertical finFET 400, where the vertical diode 500and vertical finFET 400 may be on the same coterminous region of thesubstrate surface. In various embodiments, the vertical diode 500 andvertical finFET 400 may be fabricated adjacent to each other on the samesubstrate 110, where the heavily doped region below the vertical finFET400 may be separated from the heavily doped region below the verticaldiode 500 by STI region 180.

In various embodiments, a metal contact fill 280 may be provided to eachof the electrical contacts of the vertical finFET and the verticaldiode. The vertical diode 500 and vertical finFET 400 may beelectrically isolated from each other, or the vertical diode 500 andvertical finFET 400 may be electrically connected to each other.

In an exemplary embodiment, a vertical finFET and vertical diode deviceon the same substrate may have one or more vertical fins formed on asubstrate; a doped region in the substrate located below at least one ofthe one or more vertical fins; a bottom spacer layer on the substrate110 and adjacent the sidewall of at least one of the one or morevertical fins 200; a high-K dielectric layer 250 on at least a portionof the sidewalls of at least one of the one or more vertical fins; awork function layer 260 on the high-K dielectric layer 250 on theportion of the sidewalls of at least one of the one or more verticalfins; a gate metal layer 265 on at least a portion of the work functionlayer 260; a top spacer layer 160 having a thickness, wherein a bottomsurface of the top spacer layer 160 is coplanar with a top surface ofthe high-K dielectric layer 250 on at least a portion of the sidewallsof at least one of the one or more vertical fins 200; and an oxide fill300, where the oxide fill fills in at least a portion of the spacebetween neighboring vertical finFETs 400 and/or vertical diodes 500.

An exemplary embodiment relates to a method of forming a vertical finFETand a vertical diode device on the same substrate, including forming abottom spacer layer on a heavily doped layer; forming a dummy gate layeron the bottom spacer layer; forming a top spacer layer on the dummy gatelayer; forming one or more fin trenches, where at least one of the oneor more fin trenches passes through the top spacer layer, the dummy gatelayer, and the bottom spacer layer; oxidizing at least a portion of theexposed portion of the dummy gate layer inside the one or more fintrenches to form a dummy layer liner; forming a vertical fin in at leastone of the one or more fin trenches with the dummy layer liner; formingone or more diode trenches, where at least one of the one or more fintrenches passes through the top spacer layer, the dummy gate layer, andthe bottom spacer layer; oxidizing at least a portion of the exposedportion of the dummy gate layer inside the one or more diode trenches toform a dummy layer liner; forming a first semiconductor segment in alower portion of at least one of the one or more diode trenches with thedummy layer liner; and forming a second semiconductor segment in anupper portion of the at least one of the one or more diode trenches withthe first semiconductor segment, where the second semiconductor segmentis formed on the first semiconductor segment to form a p-n junction.

Having described preferred embodiments for the fabrication of verticalfield effect transistor structure with controlled gate length (which areintended to be illustrative and not limiting), it is noted thatmodifications and variations can be made by persons skilled in the artin light of the above teachings. It is therefore to be understood thatchanges may be made in the particular embodiments disclosed which arewithin the scope of the invention as outlined by the appended claims.Having thus described aspects of the invention, with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

What is claimed is:
 1. A vertical fin field effect transistor (finFET)and a vertical diode device on the same substrate, comprising: avertical fin formed on a heavily doped layer, where the heavily dopedlayer forms a source/drain; a bottom spacer layer on the heavily dopedlayer and adjacent the sidewall of the vertical fin; a high-K dielectriclayer on at least a portion of the sidewalls of the vertical fin; a workfunction layer on the high-K dielectric layer on the portion of thesidewall of the vertical fin; a gate metal layer on at least a portionof the work function layer; a first semiconductor segment on the heavilydoped layer; and a second semiconductor segment on the firstsemiconductor segment, where the interface between the secondsemiconductor segment and the first semiconductor segment is a p-njunction.
 2. The vertical finFET and a vertical diode device of claim 1,further comprising a top source/drain on the top of the vertical fin,and a metal fill on the bottom spacer layer, where the metal fill is incontact with the gate metal layer.
 3. The vertical finFET and a verticaldiode device of claim 1, wherein the top surface of the vertical fin hasa <100> crystal orientation.
 4. The vertical finFET and a vertical diodedevice of claim 1, wherein the one or more vertical fins have a width inthe range of about 6 nm to about 20 nm.
 5. The vertical finFET and avertical diode device of claim 1, wherein the high-K dielectric layerhas a thickness in the range of about 1.5 nm to about 2.5 nm.
 6. Thevertical finFET and a vertical diode device of claim 1, wherein theinterface between the second semiconductor segment and the firstsemiconductor segment is between the top surface of the bottom spacerlayer and the bottom surface of the top spacer layer.
 7. The verticalfinFET and a vertical diode device of claim 1, wherein a dummy layerliner is on both the second semiconductor segment and the firstsemiconductor segment.
 8. The vertical finFET and a vertical diodedevice of claim 1, further comprising a counter-doped layer on or withinthe substrate, wherein the heavily doped layer is in direct contact withthe counter-doped layer.
 9. The vertical finFET and a vertical diodedevice of claim 8, wherein the heavily doped layer has a <100> or <111>crystal orientation, and the first semiconductor segments has the samecrystal orientation as the heavily doped layer.
 10. A vertical fin fieldeffect transistor (finFET) and a vertical diode device on the samesubstrate, comprising: a counter-doped layer on or within a substrate; aheavily doped layer in direct contact with the counter-doped layer; avertical fin on the heavily doped layer; a first semiconductor segmenton the heavily doped layer; and a second semiconductor segment on thefirst semiconductor segment, where the interface between the secondsemiconductor segment and the first semiconductor segment is a p-njunction.
 11. The vertical finFET and a vertical diode device of claim10, wherein the heavily doped layer has a <100> or <111> crystalorientation, and the first semiconductor segments has the same crystalorientation as the heavily doped layer.
 12. The vertical finFET and avertical diode device of claim 10, further comprising a topanode/cathode on the second semiconductor segment.
 13. The verticalfinFET and a vertical diode device of claim 10, wherein the firstsemiconductor segment and the second semiconductor segment have a widthin the range of about 6 nm to about 20 nm.
 14. The vertical finFET and avertical diode device of claim 10, wherein the second semiconductorsegment has the opposite doping as the heavily doped layer.
 15. Thevertical finFET and a vertical diode device of claim 10, wherein thevertical fin and first semiconductor segment are on a coterminous regionof a substrate.
 16. A vertical fin field effect transistor (finFET) anda vertical diode device on the same substrate, comprising: a heavilydoped layer on a substrate; a vertical fin on the heavily doped layer; afirst semiconductor segment on the heavily doped layer, where the firstsemiconductor segment and vertical fin are on the same coterminousregion of the substrate; a second semiconductor segment on the firstsemiconductor segment, where the interface between the secondsemiconductor segment and the first semiconductor segment is a p-njunction; and a dummy layer liner on both the second semiconductorsegment and the first semiconductor segment.
 17. The vertical finFET anda vertical diode device of claim 16, wherein the first semiconductorsegment has the same doping as the heavily doped layer, and the secondsemiconductor segment has the opposite doping as the heavily dopedlayer.
 18. The vertical finFET and a vertical diode device of claim 16,further comprising a shallow trench isolation (STI) region betweenneighboring regions of the heavily doped layer.
 19. The vertical finFETand a vertical diode device of claim 16, further comprising a bottomspacer layer on the heavily doped layer and a sidewall of the verticalfin, where the dummy layer liner is in contact with the bottom spacerlayer.
 20. The vertical finFET and a vertical diode device of claim 16,wherein the top surface of the first semiconductor segment has a <100>crystal orientation.